1. Field of the Invention
This invention relates to contour line plotting devices, and is more particularly directed to a device for deriving the contour lines of an object from a pair of stereophotographic films of the object.
2. Description of the Prior Art
Stereophotography of an object for study is accomplished with relative ease by the use of microscopes, stereo cameras, or other well-known devices. However, accurate analysis of the two stereophotographic films to determine the contour lines of the object has heretofore required the use of complex instruments, such as stereographs and stereocomparators. These instruments are very expensive and occupy considerable space when installed.
Stereoscopes have often been employed to compare the stereophotographic films to locate in the films the different points on the object having a selected height, that is, the points which would lie on the same contour line in a contour map of the object. However, because neither of the films provides an orthogonal plan view perpendicular to the plane of the desired contour lines, a line connecting these points in the films would represent only an approximation of a contour line containing those points. As a result, accurate analysis of the shape of an object by the use of stereoscopes has heretofore been impractical.